the breaking story overnight. This story was incredible, lara. More than two dozen people injured in a live fireworks show when the fireworks began shooting straight into the crowd. You can hear the screams there. Abc's nick watt joins us from los angeles right now. Good morning, nick. Reporter: David, good morning. Four people remain in serious condition in the hospital. In simi valley, northwest of los angeles, the so-called fireworks extravaganza, fourth of july celebration, turned into disaster. Nearly 10,000 people were packed into the park to watch the display. Then this happened. Oh. Oh, my god. Oh. Oh. Oh. Run. Reporter: Fireworks were flying thick and fast, horizontally, low to the ground, straight into the crowd. I thought it was pretty spectacular. And then, everything just went crazy. And everybody started screaming. And a black of wood about this big came shooting down. And it hit the side of my leg. Reporter: Here's how it looked from a nearby hillside. Uh-oh. Uh-oh. Reporter: At first, many revelers were unsure if all this was a thrilling part of the display. What's happening? I don't know. What the heck is going on? Reporter: Firefighters set up a triage unit at the screen. Jaci apple was at the event with his family. I witnessed a lot of people with eye injuries, arm injuries, second-degree burn injuries in the triage center. Oh, my god. Oh, oh. Oh. Run. Run. Run. Reporter: Police say some of the injured had pieces of fireworks embedded in their bodies, like shrapnel. Now, the investigation is ongoing. But officials tell abc news they think that the platforms the fireworks were loaded on just tipped over, aiming the firework, lara, at the crowd, not at the sky. So scary. Nick, thank you so much.

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